Abstract Development of vaccine technologies with therapeutic efficacy against cancer has been an elusive goal. Conventional adjuvants induce weak levels of cytotoxic CD8+ T lymphocyte (CTL) responses, while accumulating evidence suggests that simultaneous CTL and antibody (Ab) responses are needed for effective therapy. Therefore, there is a critical need for alternative approaches that can achieve strong anti-tumor immune responses. Our long-term research goal is to develop new material-based strategies that can achieve immune stimulation with potent therapeutic efficacy against cancer. Our objective in this R01 application is to delineate the key nanomaterial criteria for designing effective nano-vaccines and to utilize knowledge gained from these studies to develop a powerful vaccine technology for treatment of primary and metastatic melanomas. To that end, we have developed a novel nano-vaccine system that can (a) efficiently transport antigen (Ag) to dendritic cells (DCs); (b) promote Ag cross-presentation and cross-priming of T-cells; (c) generate significantly stronger Ag-specific CD8+ T-cell responses than conventional vaccines based on DCs, other nano-formulations, and experimental adjuvants in clinical trials; (d) enhance accumulation of anti-tumor T-cells in tumor microenvironment; and (e) induce anti-tumor immunity against primary and metastatic melanomas, in a biocompatible and safe manner. In this application, we propose to address the following questions: what are unique characteristics of our nano-vaccines that evoke such strong anti-tumor immunity, compared with other traditional cancer vaccines? Can we in turn modulate these parameters to further optimize our nano-vaccine technology and amplify anti-tumor immunity? We will evaluate outcomes of our strategy in murine models of locally and systemically disseminated melanomas. Our innovative approach employing interdisciplinary principles of materials science, bioengineering, and immunology will lead to a new vaccine nanotechnology that may eliminate primary and metastatic melanomas and improve cancer immunotherapy.